Electrochemical study of Catalase immobilized on PAOOA-modified gold electrode

Abstract

A new method for protein immobilization based on metal-ion chelation was reported in this paper. First, conductivity film poly(aniline-co-2-aminobenzoic acid) (PAOAA), which is able to conductive in neutral solution, was prepared by electrochemical deposition. The film was characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray (EDS). Then Cu²⁺ ions were adsorbed on the film as the chelating ion to immobilize catalase (Cat). The molar amount of Cu²⁺ ions in the polymer was 0.49% measured by EDS. Differential pulse voltammetry (DPV) was used to research the immobilization of Cat. The results showed that as PAOAA film forming and Cat immobilizing on the electrode surface, the peak current in 10 mmol/L K₃Fe(CN)₆/K₄Fe(CN)₆ (Fe(CN)₆^3-/4-) decreased from 121 μA (bare GE) to 92.6 and 71.8 μA respectively. This indicated that PAOAA film and Cat on the electrode could impede the charge transfer. This conclusion is same as the result of electrochemical impedance spectroscopy (EIS) studying in the process of Cat immobilization. The catalytic activity of immobilized Cat for hydrogen peroxide was studied by linear sweep voltammetry (LSV) method. Finally, chronoamperometry (CA) as the detection method, the Cat-modified electrode was able to quantitatively detect hydrogen peroxide. Moreover the Cat-modified electrode could be reuseable.